Monitoring on-premises Tomcat applications

You can configure the Tomcat light weight data collector to monitor the on-premises Tomcat applications running on Docker containers and then send monitoring data to the Unified Agent.

Before you begin

Ensure that you install the Unified Agent plug-ins for LWDC and OpenTracing. For more information, see Installing and configuring Unified Agent plug-ins.
Check whether you downloaded the Tomcat light weight data collector package. For more information, see Downloading the Tomcat light weight data collector.

Procedure

Create a silent_config_tomcat_dc.txt silent configuration file in the same directory as your Dockerfile. The silent configuration file is available in the installation package. A sample of the silent configuration is as follows:
```
JAVA_HOME=/usr
TT_STATUS=true
DD_STATUS=false
MT_STATUS=false
SERVER_NAME=TestServer
SERVER_HOME=/opt/tomcat/apache-tomcat-9.0.5
SERVER_VERSION=8
SERVER_JMX_HOSTNAME=127.0.0.1
SERVER_JMX_PORT_NUMBER=9966
SERVER_JMX_USER_NAME=
SERVER_JMX_PASSWORD=
```
where:
- JAVA_HOME is the Java home that is used by the Tomcat server. The default value is /usr.
- TT_STATUS is the flag to enable transaction tracking.
- DD_STATUS and MT_STATUS are currently not used, and can be set to default values.
- SERVER_NAME is the name of the Tomcat server that is monitored by the data collector. The default value is 'TestServer'
- SERVER_HOME is the Tomcat server home directory, default value is /opt/tomcat
- SERVER_VERSION is Tomcat server version, default value is 8. Supported values are 8 and 9.
- SERVER_JMX_HOSTNAME is the hostname where JMX for corresponding Tomcat Server will be accessible.
- SERVER_JMX_PORT_NUMBER is the port number to be configured for accessing JMX for the containerized Tomcat server.
- SERVER_JMX_USER_NAME is the user name for authentication of JMX connection. Default value is blank that indicates 'no authentication'.
- SERVER_JMX_PASSWORD is the password of JMX user for authentication of JMX connection. Default value is blank that indicates 'no authentication'
Add the following environment variables:
```
UA_LWDC_LISTENER_URL=http://<ip or host>:<port>
UA_JAEGER_ENDPOINT=http://<ip or host>:<port>/api/traces
```
where:
- ip or host is the ip or host address where you install Unified Agent in on-premises environment.
- port is the port that you configure in Installing and configuring Unified Agent plug-ins. By default, it is 8848 for UA_LWDC_LISTENER_URL and 14268 for UA_JAEGER_ENDPOINT.

Build the new docker image.

docker build -t <application image name>:<image tag>

Start your Tomcat application with the new docker image.